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1994 S10 ZR2 Wide Stance
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Discussion Starter · #1 ·
I have a 94 S10 ZR2. I don’t know if the oil pressure gauge is bad or not, but when I start the truck it hovers at about 20psi but when I start driving it and then let it idle in gear it drops below 20 and sometimes dips into the red. The truck has 150,000 miles on it and no low oil pressure or check engine light comes on. Does anyone know what’s wrong?
 

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The low oil pressure light comes on too low. It means shut the engine off now. The reason the oil pressure is dropping is probably because of bearing wear. Especially the cam bearings on a 4.3.
 

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2003 S10 4.3 2WD
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383 Posts
Replace the oil pressure sender/sensor. 150,000 miles is way too early for a 4.3 to be going down if it has been maintained.
 

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If it has been maintained. I've seen a lot of 4.3's go around 150K. ZR2's in particular because they are heavier and driven harder than most. The mid 90's engines seemed especially tough on the #4 crank bearing. Gm changed to a larger oil pump pickup tube in 96 from 5/8 to 3/4". That seemed to help.
 

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2003 S10 4.3 2WD
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If it has been maintained. I've seen a lot of 4.3's go around 150K. ZR2's in particular because they are heavier and driven harder than most. The mid 90's engines seemed especially tough on the #4 crank bearing. Gm changed to a larger oil pump pickup tube in 96 from 5/8 to 3/4". That seemed to help.
I personally owned a 4.3 TBI with over 250,000 original miles and that was on a 94 Silverado Extended Cab that was driven hard and towed heavy loads.

It is very hard to find a vehicle with a 4.3 under 200,000 miles in my state, My S10 only having 123,000 miles is a rare find here I see them selling with 300,000 miles.

I am not saying there isn't a known failure point but from my experience simply maintaining these engines they last just as long as it's big brother the 350.

But I do run Prolong in my engines which does work.
 

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I have a 01 Blazer 2wd. 165k on it. Cold start runs mid on gauge, pressure drops as it warms up. I flushed out the pan and got a little better pressure, new pressure sender gave me a little extra, but now it drops to about 8 psi at idle at operating temp. Goes up to 12 under acceleration. I've developed a knock. I've changed oil 3 times in the last 3 months and have only put less than 1200 miles on it. Last change I put in 15w40 only thing that seemed to keep the pressure up.
So now it's getting a 350. As soon as I get the time to do it.
I've only ever had 1 other 4.3 lose oil pressure. My 97 astro. I've owned 7 or 8 blazers & s10s and never an issue with any except this one and my astro.
 
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